I guess it's a valid approach - see broken window syndrome - but at the same time it's only something you can do if the police force has the luxury to respond to minor (possible) crimes. Second, it doesn't work in e.g. the US where many people are arrested, tried and jailed for small crimes, e.g. possession of marihuana. Is that a deterrent? Does it work to reduce the production, trade and consumption of drugs? Does it over time cause the prison population to reduce and prisons to close?